Stress (cont.)

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Roxanne Dryden-Edwards, MD

Dr. Roxanne Dryden-Edwards is an adult, child, and adolescent psychiatrist. She is a former Chair of the Committee on Developmental Disabilities for the American Psychiatric Association, Assistant Professor of Psychiatry at Johns Hopkins Hospital in Baltimore, Maryland, and Medical Director of the National Center for Children and Families in Bethesda, Maryland.

What is the role of the locus coeruleus in stress?

The locus coeruleus has many connections to other parts of the brain,
particularly areas that bring in and process sensory information (information
from sight, hearing, smell, taste, and touch). The locus coeruleus secretes
norepinephrine and stimulates other brain centers to do the same. It is like the
pacemaker (meaning it
controls the tempo) of the brain. Thus, it increases arousal (heightened
awareness, alertness) and vigilance (watchfulness, carefulness) and adjusts
(modulates) the action of the autonomic nervous system, which includes the SNS.
The autonomic nervous system regulates blood flow, heart rate, blood pressure,
and breathing (respiration). It can also temporarily shut down the
gastrointestinal (GI) and sexual systems until the crisis or stressful event is over. These initial
reactions, to get our blood flowing, heart pumping, and muscles energized, occur
very quickly and automatically.

How do the connections in the brain work in stress?

The HPA axis and the locus coeruleus systems are linked through the
hypothalamus and an area of the brain known as the limbic system. The limbic
system is the control area for emotion and the processing area for memory. These
linkages are critical. For example, if you see the bushes rustling, your locus
coeruleus immediately gets the stress response rolling. However, when
you see that it is not a mountain lion but a golden retriever in the bushes, your
memory of the tameness of the dog will turn off the stress response. Similarly,
if a person is nervous before a public-speaking engagement and the first minute
or two goes well, this happy feeling will turn down the activity of the locus coeruleus. These internal adjustments are why experienced public speakers often
start off with a joke. It's as much to calm themselves (if the joke goes well)
as it is to entertain you.

The connections also include the endogenous (within the body) opiate
(opium-like) system and the reward (dopamine) system. Thereby, during stress,
pain is reduced and an extremely happy feeling (euphoria) may result. These
connections partially account for "runner's high" and have a great deal to do
with why we like roller coasters and scary movies.

Here's how the connections work. The limbic system performs an emotional
analysis and memory review of the information provided by the senses. Then, the
multiplicity of connections allows us to determine whether the current stress is

one that has been mastered in the past and successfully adapted to,

not a threat at all, or

a clear and present danger.

All of this internal activity must occur in milliseconds, and it does.